Terminals may be classified as mobile/portable terminals or stationary terminals according to their mobility. Mobile terminals may also be classified as handheld terminals or vehicle mounted terminals according to whether or not a user can directly carry the terminal.
Mobile terminals have become increasingly more functional. Examples of such functions include data and voice communications, capturing images and video via a camera, recording audio, playing music files via a speaker system, and displaying images and video on a display. Some terminals include additional functionality which supports electronic game playing, while other terminals are configured as multimedia players. More recently, mobile terminals have been configured to receive broadcast and multicast signals which permit viewing of contents such as videos and television programs. In order to run such functions, a mobile terminal is basically connected to other devices or network using various communication protocols and can provide a user with ubiquitous computing. In particular, a mobile terminal has been evolved into a smart device that enables the connectivity to networks and the ubiquitous computing.
Thus, a smart device as a mobile terminal has been manufactured in a traditional size for a user to hold the smart device with a hand, whereby the user carries the smart device in a manner of holding the smart device with his hand or putting the smart device in a bag or pocket. Recently, owing to the technological developments, a smart device tends to be manufactured in further smaller size and is developed into a wearable smart device directly worn on a user's body.
The wearable smart device has been developed in wearable small size to be equipped with a variety of improved functions as a mobile terminal. On the other hand, the wearable smart device has been designed in a traditional accessory shape such as a ring, a bracelet (bangle), necklace, or the like to be wearable on a user's body. Therefore, users tend to demand wearable smart devices to have charming exteriors as accessories capable of representing their individualities. For these reasons, a wearable smart device is requested to have an improved exterior as well as various functions as a smart device. Furthermore, in order to implement the requested improved exterior and various functions, an optimized control method is requested for a wearable smart device as well.